1. Field of the Invention
The present invention relates to biomedical foam articles for the wound sector which are formed by spraying a polymer onto a wound. The polymer being sprayed onto a wound surface forms a three-dimensional body which conforms to the spatial shape of the wound and which, as well as covering the wound surface, ensures a complete and accurately fitted packing of the wound in the depth dimension as well as the other dimensions, and also has highly absorbent properties. The biomedical foam articles of the present invention are particularly useful for treating chronic wounds.
2. Description of Related Art
A chronic wound is any wound which has not epithelialized within a physiological healing time of 2-3 weeks. The most frequent forms of chronic wounds by far are decubitus ulcers (caused by chronic pressure), chronic venous ulcers of the legs (caused by chronic venous insufficiency) and diabetic ulcers (caused by angiopathy and neuropathy).
The standard treatment of chronic wounds follows the principle of “moist wound healing” with different wound contact materials. The typical materials of moist wound treatment are placed in the form of bonded fibrous nonwoven webs on the wound to obtain optimal wound covering and, by maintaining the moist wound environment, to speed wound healing.
However, extending conventional treatment methods to chronic wounds has the disadvantage that conventional wound contact materials merely cover the wound surface, but do not pack the wound three-dimensionally (especially not depthwise), which can lead to deficiencies in relation to exudate handling, a heightened risk of infection but also increased maceration at the wound edges.
The absence of wound packing in the case of cavity wounds for example can lead to exudate collecting on the floor of the wound, which as well as hindering wound healing also leads to a softening of the healthy tissue at the wound edge and ultimately to maceration. The presence of excess exudate further favours the genesis of infections.
EP 171 268 B1 discloses a wound dressing comprising a multiplicity of pieces of an absorbent material contained within a porous bag. However, such a wound dressing has one disadvantage in that it does not always lead to an accurately fitted packing of the wound in the depth dimension as well as the other dimensions. Furthermore, such a wound dressing is complicated to handle and may be difficult to keep sterile.
DE 36 38 379 discloses a method of making a medical wound dressing based on a room temperature curing, two-component polyorganosiloxane composition which gives an elastic polysiloxane foam material capable of conforming to the contours of a wound. However, the polysiloxane foam material thus formed is not highly absorbent and therefore cannot be used for wounds which secrete large amounts of wound fluid.
There is therefore a need for a novel wound contact material which optimally conforms to the often deep and/or complex wound shapes typical of many chronic wounds because its shape adapts in area and depth. Furthermore, such a wound contact material should be simple and hygienic to apply and preferably also develop an effect which is antibacterial, pain alleviating and/or wound healing accelerating. Further important properties are rapid curing and also a sufficient liquid imbibition (absorption) on the part of the material forming the wound contact material.
A prerequisite for an effective use is rapid curing (i.e. solidification of the liquid polymer to a solid foam article, determined by sensory monitoring of the viscosity) of the biomedical foam article within not more than five minutes, preferably not more than 2 minutes, more preferably not more than one minute and most preferably less than 30 seconds.
A further prerequisite is a physiological saline absorbence of 100 to 2500%, preferably 100% to 2000%, more preferably 100 to 1500% and most preferably 300 to 1500% (determined according to DIN EN 13726-1 Part 3.2) and also a water vapour transmission rate of 2000 to 12 000 g/m2 per 24 h, preferably 3000 to 10 000 g/m2 per 24 h and more preferably 3000 to 5000 g/m2 per 24 h (determined according to DIN EN 13726-2 Part 3.2). This requires that the foam have at least some open-cell content.